Alphabetic Shift
Given an array of integers, replace all the occurence of elemToReplace with subtitutionElem.

Example

• For inputArray = [1,2,1], the output should be
  elemToReplace = 1 and substitutionElem = 3 , the output should be arrayReplace(inputArray,elemToReplace,substitutionElem) = [3,2,1]

function arrayReplace(inputArray, elemToReplace, substitutionElem) {
  inputArray.forEach((element, index) => {
    if (element === elemToReplace) {
      inputArray[index] = substitutionElem;
    }
  });
  return inputArray;
}

console.log(arrayReplace([1, 2, 1], 1, 3)); // Output: [3, 2, 3]

The arrayReplace function is designed to search through an array and replace every occurrence of a specific element with a new one. This is useful when you want to transform an array without creating a completely new one or when you need to change specific values dynamically.

The function takes three arguments. The first argument, inputArray, is the original array of values. The second argument, elemToReplace, is the specific value we want to find and replace. The third argument, substitutionElem, is the new value that should replace the matched ones.

Inside the function, we use the forEach() method to loop over each element in the array. The forEach() method provides both the current element and its index. For every iteration, we check whether the current element is equal to elemToReplace. If it is, we update the value at that index in the original array with substitutionElem.

After the loop finishes, we return the modified array. This approach updates the original array in place and doesn’t create a new one. This is efficient and ideal for many simple array replacement tasks.

Here’s an example usage of the function:

```javascript console.log(arrayReplace([1, 2, 1], 1, 3)); In this example, we pass in the array [1, 2, 1] and ask the function to replace all occurrences of 1 with 3. The final result is [3, 2, 3], which is printed to the console.

This function is an elegant and straightforward solution for replacing items in an array based on a matching condition.